Fuel efficiency is of increasing importance to the operation of land vehicles in light of rising fuel prices and ecological concerns. This is especially true in the field of over-the-road highway trucks. These trucks travel great distances at relatively high speeds. Any improvement that reduces the aerodynamic drag on the truck at highway speeds can have a significant impact on the fuel economy of the truck.
Typically, over-the-highway trucks include a number of body components aimed at reducing drag and improving fuel economy. For example, some trucks have fairings installed above the roof of the cab to direct air more smoothly over the transition between the cab and the trailer. The design of hoods and fenders focuses on creating an aerodynamic surface. Another component that is often used to reduce drag is the air dam, which is a deflective shield installed between the frame of the truck and the ground. An air dam routes air around the truck's bottom smoothly to improve aerodynamic performance. Most air dams are constructed of relatively rigid materials that can be cracked or damaged by uneven road surfaces that may be found on parking lots and surface roads. Because of the potential for damage, additional clearance between the air dam and the ground may be necessary at the expense of the air dam's performance at highway speed on smooth road surfaces.